The atmospheric circulation is
well-known to exhibit substantial variability. This variability reflects weather patterns
and circulation systems that occur on many time scales, lasting from a few days
(characteristic of a normal storm system and frontal passage), to a few weeks
(characteristic of a mid-winter warm-up or a mid-summer wet period) to a few months
(characteristic of particularly cold winters or hot summers), to several years
(characteristic of abnormal winters for several years in a row), to several centuries
(characteristic of long-term climate change).

The term "teleconnection pattern" refers to a
recurring and persistent, large-scale pattern of pressure and circulation anomalies that
spans vast geographical areas. Teleconnection patterns are also referred to as preferred
modes of low-frequency (or long time scale) variability. Although these patterns typically
last for several weeks to several months, they can sometimes be prominent for several
consecutive years, thus reflecting an important part of both the interannual and
interdecadal variability of the atmospheric circulation. Many of the teleconnection
patterns are also planetary-scale in nature, and span entire ocean basins and continents.
For example, some patterns span the entire North Pacific basin, while others extend from
eastern North America to central Europe. Still others cover nearly all of Eurasia.

All teleconnection patterns are a
naturally occurring aspect of our chaotic atmospheric system, and can arise primarily a
reflection of internal atmospheric dynamics. Additionally, some of these patterns,
particularly those over the North Pacific, are also sometimes forced by changes in
tropical sea-surface temperatures and tropical convection associated with both the ENSO
cycle (Mo and Livezey 1986, Barnston and Livezey 1991) and the Madden-Julian
Oscillation (MJO).

Teleconnection patterns reflect
large-scale changes in the atmospheric wave and jet stream patterns, and influence
temperature, rainfall, storm tracks, and jet stream location/ intensity over vast areas.
Thus, they are often the culprit responsible for abnormal weather patterns occurring
simultaneously over seemingly vast distances. For example, the 1995/986 winter was very
cold and snowy over much of eastern North America, while northern Europe and Scandinavia
were cold and southern Europe/ northern Africa experienced very wet and stormy conditions.
These conditions were all partly related to the same teleconnection pattern: a strong
negative phase of the North Atlantic Oscillation (NAO).

The Climate Prediction Center
routinely monitors the primary teleconnection patterns and is involved in continuing
research to better understand their role in the global climate system. Ten prominent teleconnection
patterns can be identified in the Northern Hemisphere extratropics throughout the year, and all of these
patterns have appeared previously in the meteorological literature (Barnston and
Livezey 1987).

The following is a list of the prominent teleconnection patterns and their affected regions. Click on the desired pattern name for Discussion, Map and plotted historical Time series of that pattern.